United Nations' humanitarian chief Valerie Amos is greeted by Ali Haidar, a member of an internal Syrian opposition group which is tolerated by the regime, in Damascus, Aug. 14, 2012.
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(CBS News) DAMASCUS - United Nations emergency relief coordinator Valerie Amos said Thursday in Damascus that the humanitarian impact of Syria's civil war had more than doubled in four months, and that the spiraling violence was blocking the flow of aid to some 2.5 million people in need.

"The U.N. and its partners are reaching more people with emergency aid every month, but we are only meeting some of the needs. It's not enough," Amos told reporters in the Syrian capital, adding that "insecurity and restrictions are part of the problem."

Amos did not blame either President Bashar Assad's regime, or the rebels it is fighting for the deterioration of the situation, but she said the 18-month old crisis "has become more intense and is too often indiscriminate. All parties must do more to protect civilians. The humanitarian situation has worsened since I was here in March."

"Over a million people have been uprooted and face destitution. Perhaps a million more have urgent humanitarian needs due to the widening impact of the crisis on the economy and people's livelihoods," said Amos. "In March, we estimated that a million people were in need of help. Now as many as 2.5 million are in need of assistance and we are working to update our plans and our funding requirements."

Amos, a member of the British House of Lords, met during her three-day visit to Syria with Gen. Babacar Gaye, head of the U.N. monitoring mission in the country known as UNSMIS, Syrian Minister for National Reconciliation Ali Haidar, Foreign Minister Walid Muallem and Prime Minister Wael Al-Halaqi to discuss ways to increase humanitarian aid to civilians trapped or displaced by the fighting.

Amos spoke a day after Syrian warplanes bombarded the rebel-held town of Azaz, about 30 miles north of the country's largest city, Aleppo. According to opposition groups, at least 23 people were killed in the air strikes, and Associated Press reporters said at least one young child was among those killed.

Opposition activists claim at least 20,000 people have died since the uprising began as peaceful demonstrations against Assad's rule.